The present invention relates to an electrical wiring harness structure for a vehicle, for constituting a multiplex transmission network in a vehicle.
As a conventional body structure of a vehicle, a so-called unit body structure is adopted, and a desired effect can be obtained from the viewpoint of improvement in mechanical strength of the vehicle body. However, since the unit body structure forms a passenger room space before equipments (e.g., seats) in the passenger room are assembled, these equipments in the passenger room can only be assembled in the passenger room space from aside through a door opening portion, resulting in very poor operability.
As a means for solving this problem, as disclosed in Japanese Utility Model Laid-Open No. 62-105876, a technique for dividing a vehicle body into upper and under bodies in advance is known. With this dividing technique, the equipments (e.g., seats) in the passenger room can be assembled from above to a floor portion mounted on the under body before the upper body is joined to the under body, thereby greatly improving operability. As an improvement to this technique, the following method is also proposed. In this method, a vehicle body is divided into not only upper and under bodies, but also a block of an engine room portion, a block of a passenger room portion, and a block of a luggage room portion in the front-to-rear direction of the vehicle body, and after equipments and electrical components necessary for these blocks are assembled, these blocks are connected to complete a vehicle body. With this method, these blocks are parallelly assembled in corresponding assembling processes, and thereafter, are combined to complete a vehicle body, thus further improving operability.
However, since the number of electrical components such as switches, sensors, actuators, and the like is increased along with development of electronics for vehicles, enlarged and complicated wiring harnesses for connecting electrical components pose a serious problem. For this reason, as described above, when a vehicle body is divided into a plurality of blocks, and the blocks are combined after equipments and electrical components are assembled in units of blocks, the number of wires for connecting the electrical components in each block becomes very large, and a cumbersome operation is required to connect these wires in units of blocks, resulting in many connection errors, and the like. More specifically, a method of dividing a vehicle body into modules, and assembling a vehicle in units of modules is being promoted, while a problem of a complicated wiring structure caused by complicated electrical components is left unsolved. In practice, it is not easy to realize a divisional assembling method of a vehicle body.
As a method of eliminating enlarged and complicated wiring harnesses for connecting the electrical components, a multiplex transmission system, in which one transmission path is commonly used by a large number of electrical components, has received a lot of attention. More specifically, nodes for various electrical components, and control nodes for engine control (EGI), four-wheel steering control (4WS), anti-lock brake control (ABS), and the like are connected to a multiplex transmission path, thus constituting a time-divisional multiplex transmission network. As a wiring harness constituting the multiplex transmission path, a communication line comprising a twisted pair wire is normally used.
The application of the multiplex transmission network to a vehicle is advantageous from the viewpoint of a decrease in the number of wires used in signal transmission among blocks, and helps to achieve a module structure of a vehicle body.
As a conventional electrical wiring harness structure upon constitution of the multiplex transmission network in a vehicle, a structure disclosed in Japanese Patent Laid-Open No. 2-184210 is known. This application relates to a branch system of a transmission path of a multiplex transmission network. Of the communication line constituting the transmission path, a portion to be branched is led into a housing of a branch connector. A branch bar having a forked end is arranged in the housing. Male terminals are fixed to the distal ends of the forked end side, and a female terminal is fixed to the opposite end. The communication line led into the housing is cut, and the female terminals are fixed to the two cut ends of the communication line. The female terminals are connected to the male terminals of the branch bar. When the branch connector whose female terminal of the branch bar extends outwardly is used, male-female connection to a connector of the branch transmission path can be realized.
However, even if the conventional electrical wiring harness structure is applied to merely branch signal lines, the above-mentioned module structure of the vehicle body cannot be satisfactorily realized.